Shock wave therapy of kidney stones, also known as shock wave lithotripsy (SWL), is a medical procedure in which focused acoustic shock waves are used to pulverize kidney stones into pieces that are sufficiently small to pass naturally from the body. It is termed a non-invasive procedure because the shock waves are generated outside the body, i.e., acoustic waves are transferred into the body through a coupling medium. However, SWL is not a benign procedure, since it is known that shock waves can cause acute and chronic complications to kidneys and other tissues. Further, tissue damage is dose-dependent, where dose is measured in part by the number of shock waves applied during a treatment session. The fragmentation of kidney stones is difficult to assess during SWL, and there is little unambiguous feedback available to a physician regarding the extent of fragmentation.
It would be desirable to provide physicians techniques that enable the fragmentation of kidney stones to be evaluated in order to determine when sufficient number of shock waves have been administered, so as to minimize the dose provided to the patient, thereby minimizing any negative effects.